A battery pack includes battery cell having a discharge valve opened when an internal pressure exceeds a set pressure, and case housing battery cell. case has opening, and opening is blocked by porous plate made of resin. porous plate has a plurality of through-holes, an expansion gap of a discharge gas is formed by stacking a plurality of the porous plates, through-holes provided in each of porous plates are arranged at non-facing positions not facing through-holes provided in adjacent another porous plate, and the discharge gas of the discharge valve passes through through-holes provided in porous plates and the expansion gap and is discharged to an outside of the case.
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1. A battery pack comprising:
a battery cell having a discharge valve opened when an internal pressure of the battery cell exceeds a set pressure; and
a case housing the battery cell,
wherein
the case includes an opening,
the opening is blocked by a porous plate made of resin,
the porous plate has a plurality of through-holes,
an expansion gap of a discharge gas is defined by stacking a plurality of the porous plates each being the porous plate,
the plurality of through-holes provided in each of the porous plates are arranged at non-facing positions not facing the plurality of through-holes provided in adjacent another porous plate, and
the discharge gas of the discharge valve passes through the plurality of through-holes provided in the porous plates and the expansion gap and is discharged to an outside of the case.
2. The battery pack according to
each of the porous plates stacked on top of each other includes a rectangular shape, and
the porous plates are stacked on inside out with a diagonal line of the rectangular shape as a symmetric axis, and the through-holes of the porous plates stacked are arranged at non-facing positions.
4. The battery pack according to
5. The battery pack according to
6. The battery pack according to
7. The battery pack according to
the case is a rectangular cuboid coupling with peripheral walls around a surface plate including a square shape,
the battery cell is disposed in parallel with the surface plate, and is housed in a state in which a valve side end surface on which the discharge valve is provided faces an inside of a peripheral wall among the peripheral walls, and
the porous plates are provided on the surface plate.
8. The battery pack according to
9. The battery pack according to
10. The battery pack according to
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This application is a U.S. national stage application of the PCT International Application No. PCT/JP2019/048016 filed on Dec. 9, 2019, which claims the benefit of foreign priority of Japanese patent application No. 2019-011547 filed on Jan. 25, 2019, the contents all of which are incorporated herein by reference.
The present invention relates to a battery pack that houses a battery that can be charged in an exterior case.
In recent years, a battery pack used as a power supply of a portable electric device has been further required to have a high output, and a non-aqueous electrolyte secondary battery such as a lithium-ion battery having excellent efficiency per unit volume has been adopted. Although the lithium-ion battery has a high output, an internal pressure may increase for some reason. In order to ensure safety against an increase in the internal pressure of the battery, a discharge valve opened at a set pressure to prevent rupture is provided. When the discharge valve is opened, the battery is in an abnormal heat generation state, and a high-temperature gas is vigorously ejected from the discharge valve. A battery pack in which a vent hole is provided in a case and a mesh member made of metal is provided in the vent hole in order to discharge a discharge gas discharged from a discharge valve to the outside of the case has been developed.
PTL 1: Unexamined Japanese Patent Publication No. 2009-212081
In the battery pack of PTL 1, the metal mesh member is provided in the vent hole of the exterior case, and the discharge gas ejected from the discharge valve is quickly discharged to the outside. In this battery pack, it is difficult to safely discharge the high-temperature discharge gas vigorously ejected from the battery cell to the outside. In particular, since the discharge gas ejected from the discharge valve of the lithium-ion battery which is the non-aqueous electrolyte secondary battery is vigorously ejected at an abnormally high temperature of 400° C. or higher, adverse effects such as smoking, ignition, and the like of the gas passed through the mesh member and discharged to the outside on the outside of the case cannot be guaranteed.
The present invention has been made based on such findings of the present inventors. A main object of the present invention is to provide a battery pack that ensures safety by suppressing adverse effects caused by a high-temperature discharge gas ejected from a discharge valve of a battery.
A battery pack of the present invention includes battery cell 1 having a discharge valve opened when an internal pressure exceeds a set pressure, and case 2 housing battery cell 1. Case 2 has opening 26, and opening 26 is blocked by porous plate 5 made of resin. Porous plate 5 has a plurality of through-holes 5a, expansion gap 8 of a discharge gas is formed by stacking a plurality of porous plates 5, through-holes 5a provided in each of porous plates 5 are arranged at non-facing positions not facing through-holes 5a provided in adjacent another porous plate 5, and the discharge gas of the discharge valve passes through through-holes 5a provided in porous plates 5 and expansion gap 8 and is discharged to an outside of the case.
The above battery pack can enhance safety by suppressing adverse effects caused by the high-temperature discharge gas ejected from the discharge valve of the battery cell. This is because in the above battery pack, the porous plates as the plastic plates having a large number of through-holes are provided in the opening of the case, the plurality of porous plates is stacked with the expansion gap, the through-holes of the stacked porous plates are arranged at the non-facing positions, and the discharge gas passes through the through-holes of the porous plates, diffuses while being adiabatically expanded in the expansion gap, further passes through the through-holes, and is discharged to the outside of the case. The discharge gas exhausted to the outside of the case in the above state is ejected from the battery cell, is dispersed in and passes through the plurality of through-holes provided in the porous plates inside the case, and passes through the through-holes. Thereafter, the discharge gas is ejected into the expansion gap, and is adiabatically expanded. The temperature of the discharge gas is lowered, and the discharge gas collides with the surface of the stacked porous plate on the discharge side. Thereafter, the discharge gas is dispersed, the energy is attenuated, and the discharge gas is exhausted to the outside of the case even in the state of passing through the through-holes of the porous plates. The discharge gas passes through the plurality of through-holes, and is redirected by colliding with the surface of the porous plate on the discharge side while the discharge gas is decreased in temperature by being adiabatically expanded in the expansion gap. The energy is attenuated even while the discharge gas is dispersed, the path through which the discharge gas passes is lengthened, and the discharge gas is dispersed in the large number of through-holes and is discharged to the outside. Thus, the discharge gas is not vigorously exhausted to the outside of the case in a state of being discharged to the outside of the case, and safety can be enhanced by suppressing adverse effects such as smoking and ignition.
A first invention of the present invention is a battery pack including a battery cell having a discharge valve opened when an internal pressure exceeds a set pressure, and a case housing the battery cell. The case has an opening, the opening is blocked by a porous plate made of resin, the porous plate has a plurality of through-holes, an expansion gap of a discharge gas is formed by stacking a plurality of the porous plates, the through-holes provided in the porous plate are arranged at non-facing positions not facing the through-holes provided in adjacent another porous plate, and the discharge gas of the discharge valve passes through the through-holes provided in the porous plates and the expansion gap and is discharged to an outside of the case.
In a second invention of the present invention, each of the porous plates stacked on top of each other has a rectangular shape, the porous plates are stacked on inside out with a diagonal line of the rectangular shape as a symmetric axis, and the through-holes of the stacked porous plates are arranged at non-facing positions. In a third invention of the present invention, each of the porous plates has a square shape. The battery pack having this structure has an advantage that since the through-holes can be arranged at the non-facing positions by stacking the porous plates having the same shape, it is possible to produce a large amount of battery pack while reducing manufacturing cost.
In a fourth invention of the present invention, the through-holes of the porous plates stacked on an inner side of the case are larger than the through-holes of the porous plates stacked on an outer side of the case. In the battery pack having this structure, since the through-holes of the porous plate on the inner side through which the discharge gas ejected from the discharge valve first permeates is set to be larger than the porous plate on the outer side, the discharge gas ejected from the discharge valve can smoothly pass through the through-holes and can be quickly exhausted to the outside of the case.
In a fifth invention of the present invention, each of the porous plate is integrally molded with protrusions, and the expansion gap is formed in a state in which the porous plates are stacked. In the battery pack having this structure, the expansion gap can be easily and accurately provided at a predetermined interval by the protrusions in a state in which the plurality of porous plates is stacked.
In a sixth invention of the present invention, an inner diameter of each of the through-holes of each of the porous plates is equal to or more than 0.5 mm and is equal to or less than 3 mm. In the structure in which the through-hole of the porous plate has the inner diameter as described above, the discharge gas can be smoothly discharged to the outside of the case while the permeation resistance of the discharge gas is increased.
In a seventh invention of the present invention, the case is a rectangular cuboid obtained by coupling peripheral walls around a surface plate having a square shape, the battery cell is disposed in parallel with the surface plate, and is housed in a state in which a valve side end surface on which the discharge valve is provided faces an inside of the peripheral wall, and the porous plates are provided on the surface plate. In the battery pack having this structure, since an ejection direction of the discharge gas ejected from the battery cell and a direction in which the discharge gas passes through the through-holes of the porous plates are set to directions intersecting each other, the discharge gas ejected from the battery cell can be discharged to the outside while the discharge gas is redirected in the case, and the energy of the discharge gas can be efficiently attenuated.
In an eighth invention of the present invention, in each of the porous plates, the through-holes are provided at intersections of a checkerboard lattice. In the battery pack having this structure, the through-holes of the porous plates stacked on top of each other and facing each other can be efficiently arranged at the non-facing positions while a large number of through-holes are efficiently provided in the porous plates.
In a ninth invention of the present invention, a label peeled off or melted by the discharge gas discharged from the discharge valve is attached to a surface of the porous plate in the case. In this battery pack, since the discharge side of the porous plate is blocked by the label, it is possible to effectively prevent foreign substances from passing through the through-holes of the porous plates from the outside to the inside of the case.
In a tenth invention of the present invention, the battery cell is a non-aqueous electrolyte secondary battery. In an eleventh invention of the present invention, the battery cell is a lithium-ion battery.
Hereinafter, the present invention will be described in detail with reference to the drawings. In the following description, terms (for example, “upper”, “lower”, and other terms including these terms) indicating specific directions and positions are used as necessary, but these terms are used to facilitate understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meanings of these terms. Parts denoted by identical reference marks in a plurality of drawings indicate identical or equivalent parts or members.
The following exemplary embodiments illustrate specific examples of the technical idea of the present invention, and do not limit the present invention to the following exemplary embodiments. Unless otherwise specified, dimensions, materials, shapes, relative arrangements, and the like of constituent components to be described below are not intended to limit the scope of the present invention, but are intended to be illustrative. Contents described in one exemplary embodiment and example are also applicable to other exemplary embodiments and examples. Sizes, positional relationships, and the like of members illustrated in the drawings may be exaggerated in order to clarify the description.
Battery pack 100 illustrated in
(Battery Cell 1)
Battery cell 1 is a battery having a cylindrical shape. In the cylindrical battery, an electrode and an electrolytic solution are housed in a metal case having a cylindrical shape. The metal case has a sealed structure in which a sealing plate is airtightly fixed to an opening of an exterior can blocking a bottom. The exterior can is manufactured by pressing a metal plate. The sealing plate is airtightly fixed by being crimped to a peripheral edge of the opening of the exterior can with an insulating packing interposed therebetween.
Although not illustrated, a discharge valve on the sealing plate is provided in battery cell 1 in order to prevent damage due to an abnormally high internal pressure of the metal case. In the discharge valve, an opening through which an internal gas and the like are discharged in an opened state is provided in the sealing plate. However, in the battery cell, the discharge valve and the opening thereof may be provided at a bottom portion of the exterior can. When the internal pressure becomes higher than a set pressure, for example, 1.5 MPa, the discharge valve is opened to prevent destruction of the metal case due to an increase in the internal pressure. The discharge valve is opened in an abnormal state. Accordingly, in a state in which the discharge valve is opened, a temperature of battery cell 1 is also very high. Thus, the gas and the electrolytic solution (ejected matter) discharged from the opened discharge valve have an abnormal high temperature. Particularly, in a battery pack in which battery cell 1 is a non-aqueous electrolyte secondary battery such as a lithium-ion battery, a discharge gas has an abnormal high temperature of 400° C. or higher. Since the lithium-ion battery is filled with a non-aqueous electrolytic solution, when the electrolytic solution is discharged to the outside of the case at a high temperature, the electrolytic solution may be ignited by being in contact with air, and may have an abnormal higher temperature. In not only the lithium-ion battery but also other chargeable batteries, since the discharge gas ejected from the opened discharge valve has a high temperature, it is important to attenuate the energy of the discharge gas and exhaust the discharge gas to the outside of the case for enhancing safety.
In battery pack 100 of
(Circuit Board 3)
An electronic component (not illustrated) connected to battery cells 1 to achieve a protection circuit for battery cells 1 is mounted on circuit board 3. The protection circuit is a circuit that prevents overcharge and overdischarge of battery cells 1, a circuit that prevents overcurrent, or a circuit that interrupts current in a state in which the temperature rises abnormally. In battery pack 100 illustrated in
(Case 2)
Case 2 is made of a thermoplastic resin, is molded in a rectangular box shape as a whole, and has battery cells 1 and circuit board 3 built therein. Case 2 in the drawing includes upper case 2A and lower case 2B. At lower case 2B and upper case 2A, peripheral wall 22 is provided around surface plate 21 having a quadrangular shape. Lower case 2B and upper case 2A are coupled with opening end surfaces of peripheral wall 22 as mating surfaces. Peripheral wall 22 of lower case 2B and upper case 2A includes side walls 23 on both sides extending in a longitudinal direction of rectangular surface plate 21 and end walls 24 orthogonal to side walls 23. Heat-resistant covers 6 is arranged inside end walls 24 facing the openings of the discharge valves. Heat-resistant cover 6 is a heat-resistant plate or sheet that withstands the temperature of the discharge gas. Heat-resistant cover 6 prevents the discharge gas ejected from the discharge valve from being directly ejected to end wall 24, and scatter the discharge gas in all directions. A case having end walls made of a heat-resistant material can scatter the discharge gas around by end walls without providing the heat-resistant covers.
In case 2, opening 26 is provided in surface plate 21, and resin porous plate 5 having a plurality of through-holes 5a is disposed in opening 26. In case 2 of
(Porous Plate 5)
Opening 26 is blocked by porous plate 5 in which the discharge gas can pass. Porous plate 5 is bonded and fixed to surface plate 21 by a structure such as adhesion or welding, or is fixed by a fitting structure. Porous plate 5 is fixed so as not to form a gap between the porous plate and opening 26. The plurality of porous plates 5 is stacked so as to attenuate and exhaust the energy of the discharge gas. Expansion gap 8 of the discharge gas is provided between stacked porous plates 5. Through-holes 5a of each of stacked porous plates 5 have a structure in which through-holes 5a of adjacent porous plates 5 are arranged at non-facing positions not facing each other and the discharge gas does not flow linearly through the plurality of porous plates 5 to be exhausted. Porous plate 5 is obtained by molding a thermoplastic resin into a plate shape, and a plurality of through-holes 5a is provided in the porous plate.
Plastic having heat resistance capable of attenuating the energy of the discharge gas and exhausting the discharge gas to the outside is used as porous plate 5. Although it is ideal that porous plate 5 is molded by plastic having heat resistance that is not thermally deformed by the temperature of the discharge gas, the structure in which the plurality of porous plates 5 is stacked with expansion gap 8 may not have heat resistance that all porous plates 5 are not thermally deformed by the discharge gas. This is because even though porous plate 5 on the inner side is thermally deformed, the safety of the battery pack can be ensured by maintaining a state in which porous plate 5 on the outer side can attenuate and exhaust the discharge gas by the plurality of remaining through-holes 5a. There are characteristics that porous plate 5 obtained by stacking a plurality of sheets can be produced in large quantities at low cost by injection molding with a thermoplastic resin such as polycarbonate. However, the present invention does not specify the plastic of porous plate 5, and the porous plate can be molded with a thermoplastic resin having more excellent heat resistance, for example, a thermoplastic resin such as a nylon resin or a fluorocarbon resin, and can also be molded with plastic having more excellent heat resistance such as a silicone resin or a polyimide resin.
In porous plate 5 illustrated in plan view of
Since porous plate 5 can lengthen through-hole 5a to increase the permeation resistance of the discharge gas by increasing a thickness, the thickness of porous plate 5 is preferably 1 mm to 3 mm. However, in the present invention, the inner diameter of through-hole 5a and the thickness of porous plate 5 are not specified to the above ranges, and the porous plate can have a shape in which the energy of the discharge gas is attenuated to exhaust the discharge gas by providing a plurality of smaller through-holes or a small number of larger through-holes and thinning or thickening the porous plate. The pitch of through-holes 5a is set to a dimension in which through-holes 5a of facing porous plates 5 are arranged at non-facing positions and a part of through-holes 5a is not arranged at a facing position of stacked porous plates 5. As illustrated in the plan view of
As illustrated in
Protrusions 2b are scattered and arranged on an outer periphery of porous plate 5 and are also arranged in a central portion if necessary, and can be stacked while expansion gap 8 is set to be constant.
Although not illustrated, the porous plate can be formed into a shape in which the through-holes can be arranged at non-facing positions by alternately stacking porous plates molded in an identical shape with a diagonal line with as a symmetry axis. This porous plate has, for example, a square outer shape, and thus, the through-holes can be arranged at non-facing positions while a plurality of porous plates is ideally stacked. The porous plates can also be molded such that the through-holes can be arranged at non-facing positions in a state in which the porous plates formed in the identical shape are stacked inside out with left and right center lines as symmetry axes or are stacked inside out with upper and lower center lines as symmetry axes. In this structure, for example, the porous plates each having the rectangular outer shape are alternately inverted and stacked, and thus, the through-holes can be arranged at the non-facing positions. The porous plates can also be molded such that the through-holes can be arranged at the non-facing positions by rotating the porous plates by 90 degrees or 180 degrees in a horizontal plane and stacking the porous plates formed in the identical shape. These porous plates have an advantage that a large amount of production can be performed while manufacturing cost is reduced since the through-holes can be arranged at the non-facing positions in a state in which the plurality of stacked plates is stacked while the porous plates having the identical shape are used.
Although not illustrated, in the porous plates stacked vertically and coupled to each other, positioning recesses and positioning protrusions fitted to each other can be provided at positions facing each other on the porous plates. In this structure, the positioning recesses and the positioning protrusions are fitted, and thus, the stacked porous plates can be coupled while being easily and reliably positioned. In particular, in the porous plates in which the through-holes can be arranged at the non-facing positions by stacking the upper and lower porous plates in a specific orientation, the stacked porous plates can be reliably coupled in a correct direction by fitting the positioning recesses and the positioning protrusions to each other, and thus, the through-holes can be ideally arranged at the non-facing positions.
In battery pack 100, diffusion space 25 is provided inside case 2. In battery pack 100, the discharge gas ejected from the discharge valve is ejected into diffusion space 25, and the energy is attenuated in diffusion space 25. Thereafter, the energy is attenuated in through-holes 5a provided in stacked porous plates 5 and expansion gap 8 provided between porous plates 5, and the discharge gas is discharged to the outside of the case. Through-holes 5a attenuate the energy of the discharge gas by the permeation resistance through which the discharge gas permeates, and expansion gap 8 causes the discharge gas having permeated through through-holes 5a to collide with the surfaces of porous plates 5 and attenuates the energy of the discharge gas.
Battery pack 100 illustrated in a schematic perspective view of
The discharge gas ejected into the case from the discharge valves flows in directions indicated by arrows in
In case 2 illustrated in
As illustrated in a cross-sectional view of
The present invention can be effectively used for a battery pack that safely exhausts a discharge gas.
Wakabayashi, Takeaki, Takeda, Kensaku
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| Jun 24 2021 | WAKABAYASHI, TAKEAKI | SANYO ELECTRIC CO , LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 058026 | /0332 | |
| Jun 24 2021 | TAKEDA, KENSAKU | SANYO ELECTRIC CO , LTD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 058026 | /0332 | |
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